How do microbial communities respond to perturbations?

Daniel RODIRGUEZ AMOR (Graz): Microbial communities play myriad roles in ecosystems, from fixing atmospheric nitrogen, to recycling organic matter to promoting host health. In many cas-es, e.g. in the human gut ecosystem, these communities display alternative sta-ble states associated to health and dysbiosis. Not only this, but our daily life commonly gives rise to perturbations (changes in diet, infections, or exposure to antibiotics) that can induce community shifts towards alternative stable states. However, the mechanisms driving these shifts are, in general, poorly understood. In this talk, I will introduce an experimental model system that we use to interro-gate, quantitatively, microbial community resilience to perturbations and transi-tions between stable states. I will show that the arrival of an invader species can often induce transitions between stable states of microbial communities, even if the invader itself does not survive the transition. I will also address how this ex-perimental community responds to antibiotic perturbations. In this case, our theo-retical model predicts, and experiments confirmed, that ecological parameters such as growth and dispersal rates can counteract antibiotic susceptibility in shaping community resilience to antibiotics.